1. Field of the Invention
The present invention relates to a signal input device for inputting a signal to an electronic device upon operation of a control, the signal input device being suitably used as, for example, a controllers for game machines.
2. Description of the Related Art
FIG. 7 is an exploded perspective view of a controller 100 used as a signal input device for game machines, which has been previously developed by the assignee of the present invention. Referring to FIG. 7, numeral 10 denotes an upper case constituting an upper side of a housing of the controller 10, and 20 denotes a lower case constituting a lower side of the controller housing. Also, numeral 30 denotes a flexible board arranged in an inner space defined by the upper case 10 and the lower case 20, and 40 denotes a plate used for pressing the flexible board 30 to be fixed to an inner surface of the upper case 10.
On an upper surface of the upper case 10, a cross key (digital control) 11 is provided at one end and a key top (digital control) 12 comprising four kinds of keys is provided at the other end. Holes 14, 14 are formed in the upper case 10 at an end on the rear side (closer to the player) . Control levers 22, 22 serving as controls, described later, are inserted respectively through the holes 14, 14 such that their heads project out of the upper surface of the upper case 10.
The plate 40 is attached to the lower case 20, and the flexible board 30 is attached onto the plate 40. Further, the lower case 20 is provided with a connector (not shown) connected to a cable 23 for taking out a signal from the flexible board 30.
An analog input section of the controller 100 will be described below. Note that two control levers 22 are provided, but the following description is made of one control lever 22.
First, as shown in FIG. 8, the control lever 22 is disposed above the flexible board 30, and mainly comprises a tubular stick 22a and a substantially disk-shaped stick knob 22b provided at an upper end of the stick 22a in coaxial relation. A larger-diameter pressing portion 22d is formed at a lower end of the stick 22a. 
Then, a skirt-shaped movement transmitting member 45 is fixedly attached in surrounding relation to the stick 22a, and four fitting recesses 45a are provided in a lower surface (surface on the side closer to the lower case 20) of the movement transmitting member 45 with equal angular intervals. The fitting recesses 45a are fitted respectively to projections 51a of support members 51 each supporting an electrically conductive rubber 50 which serves as an electrically conductive elastic member.
The support member 51 has an attachment surface 51b for the electrically conductive rubber 50 on the side facing the flexible board 30, and also has the projection 51a provided on the same side as the movement transmitting member 45. The electrically conductive rubber 50 having a pyramid-shaped fore end is attached to the attachment surface 51b. 
The projections 51a of the support members 51 are fitted respectively to the corresponding fitting recesses 45a provided in the movement transmitting member 45, whereby the four electrically conductive rubbers 50 are provided on the movement transmitting member 45. Further, as shown in FIG. 7, the four support members 51 including the electrically conductive rubbers 50 attached thereto are arranged to lie in four directions, i.e., in the +X-, xe2x88x92X-, +Y- and xe2x88x92Y-directions, about a neutral axis N of the control lever 22.
On the other hand, as shown in FIGS. 7 and 8, resistance elements 60 are formed on an upper surface of the flexible board 30 in one-to-one facing relation to the positions of the electrically conductive rubbers 50 provided on the movement transmitting member 45 which is arranged above the upper surface of the flexible board 30. Holes 72 are formed in the flexible board 30 in positions facing the pressing portions 22d provided at the lower ends of the sticks 22a of the control levers 22 such that coil springs 71 placed in the holes 72 are projected from the side of the plate 40 toward the side of the control lever 22. Further, push switches 32, 34 are disposed on the flexible board 30 at positions respectively facing individual keys of the cross key 11 and the key top 12.
The push switches 32, 34 are each a digital switch comprising, though not shown, an upper contact and a lower contact which are each made of electrically conductive rubber or the like and are arranged within a dome-shaped member made of rubber or the like in mutually facing relation. When the switch is pressed externally of the dome-shaped member, the upper contact and the lower contact are contacted with each other for ON/OFF control. Thus, by operating the individual keys of the cross key (digital control) 11 and the key top (digital control) 12 provided on the upper surface of the upper case 10, a digital signal from the operated one of the push switches 32, 34 is inputted to the game machine through the flexible board 30 and the cable 23.
An assembled state of the analog input section will be described below.
In the assembled state, as shown in FIG. 8, the control lever 22 is arranged such that a lower end portion of the stick 22a is positioned in the inner space defined between the upper cover 10 and the plate 40, and the stick knob 22b is projected out of the hole 14 formed in the upper cover 10. Also, an upper end of the coil spring 71 projecting out of the plate 40 is fitted to the pressing portion 22d provided at the lower end of the stick 22a. With the stick 22a biased upward under a biasing force of the coil spring 71, an upper surface of a skirt portion 45b of the movement transmitting member 45 fixedly attached around the stick 22a is biased in the above inner space so as to abut with an inner wall surface 10a of the upper cover 10 surrounding the hole 14, whereby the control lever 22 is held in a neutral position.
Further, when the control lever 22 is in the neutral position, i.e., in the inoperative state, a gap is left between the electrically conductive rubber 50 provided on the attachment surface 51b of the support member 51, which is attached to the movement transmitting member 45, and the resistance element 60 formed on the upper surface of the flexible board 30, so that a planar analog switch is constructed between them.
The operation of the analog input section will be described below.
The above-mentioned analog switch is constructed to be able to change the amount of resistance with a change in contact area between the electrically conductive rubber 50 and the resistance element 60 depending on the azimuth and the tilt angle in and through which an actuating point P of the control lever 22, shown in FIG. 9, is moved from the neutral axis N. More specifically, the electrically conductive rubber 50 has a smaller resistance value per unit area than the resistance element 60. Therefore, as the contact area increases, the resistance value of the resistance element 60 (combined with the electrically conductive rubber 50) is reduced and a current flowing through the resistance element 60 (including the electrically conductive rubber 50) is increased.
For example, when the control lever 22 is in the inoperative state shown in FIG. 8, the actuating point P of the control lever 22 lies on the neutral axis N, and the four electrically conductive rubbers 50 attached to the movement transmitting member 45 are not contacted with the corresponding resistance elements 60 as shown. In this condition, therefore, the resistance value of the resistance element 60 is not changed and a current in the normal state flows.
Then, when the control lever 22 is tilted in the xe2x88x92X-direction as shown in FIG. 9, the actuating point P of the control lever 22 is moved in the xe2x88x92X-direction to a position shifted from the neutral axis N at which the actuating point P has been positioned in the inoperative state. At this time, the electrically conductive rubber 50 attached to the movement transmitting member 45 and positioned in the xe2x88x92X-direction is pressed by the movement transmitting member 45 to be brought into contact with the corresponding resistance element 60 as shown in FIGS. 9 and 10. On the other hand, the electrically conductive rubbers 50 positioned in the +X-, xe2x88x92Y-, and +Y-directions are not contacted with the corresponding resistance elements 60. In this case, therefore, the resistance value provided by a combination of the electrically conductive rubber 50 in the xe2x88x92X-direction and the corresponding resistance element 60 is changed, whereas the resistance values provided by combinations of the electrically conductive rubbers 50 positioned in the +X-, xe2x88x92Y-, and +Y-directions and the corresponding resistance elements 60 are not changed and the current in the normal state flows.
When the control lever 22 is tilted midway between the xe2x88x92X- and xe2x88x92Y-directions, the actuating point P of the control lever 22 is moved midway between the xe2x88x92X- and xe2x88x92Y-directions to a position shifted from the neutral axis N at which the actuating point P has been positioned in the inoperative state. At this time, the electrically conductive rubbers 50 attached to the movement transmitting member 45 and positioned in the xe2x88x92X- and xe2x88x92Y-directions are pressed by the movement transmitting member 45 to be brought into contact with the corresponding resistance elements 60, but the contact area in this case is smaller than that in the case of tilting the control lever 22 in the xe2x88x92X-direction only as shown in FIG. 9. Accordingly, the resistance value is larger than the case of tilting the control lever 22 in the xe2x88x92X-direction only, and a smaller current flows. On the other hand, the electrically conductive rubbers 50 positioned in the +X- and +Y-directions are not contacted with the corresponding resistance elements 60. Therefore, the resistance values provided by combinations of the electrically conductive rubbers 50 positioned in the +X- and +Y-directions and the corresponding resistance elements 60 are not changed and the current in the normal state flows.
Thus, the analog input section can detect the azimuth and the tilt angle in and through which the actuating point P of the control lever 22 has been moved, by measuring voltage changes in accordance with analog changes in currents flowing through the resistance elements 60. Then, the analog input section can input detected signals, as analog signals, to the game machine through the flexible board 30 and the cable 23.
Next, the points to be improved in the above-described analog input section of the controller 100 will be described.
As one point, the control lever 22 is not supported such that the center of tilting of the control lever 22 will not move. Therefore, when the actuating point P is tilted in the xe2x88x92X-direction as shown in FIG. 9, the control lever 22 is caused to translate due to a play between the pressing portion 22d formed at the lower end of the stick 22a and the coil spring 71, a deformation of the coil spring 71 in the xe2x88x92X-direction at the position of the pressing portion 22d, etc. This means that the fore end of the electrically conductive rubber 50 on the support member 51 attached to the movement transmitting member 45, which is in turn fixedly attached to the stick 22a, is not determined in its position as desired. Accordingly, as shown in FIG. 11, the position (indicated by arrow in the drawing) of the fore end of the electrically conductive rubber 50 may deviate from the center of the resistance element 60 to such an extent that, when the electrically conductive rubber 50 is pressed against the resistance element 60, the electrically conductive rubber 50 comes outside the edge of the resistance element 60 in the xe2x88x92X-direction and protrudes over the flexible board 30. In such a condition, the change in the resistance value is reduced and saturated even with further pressing of the electrically conductive rubber 50 because a contact area Sxe2x80x2 in the condition of FIG. 11 is smaller than a contact area S resulted when the electrically conductive rubber 50 is completely contacted with the resistance element 60 as shown in FIG. 10.
The above problem can be overcome by setting the resistance element 60 to have a greater length beforehand in consideration of that the position of the electrically conductive rubber 50 may deviate with respect to the resistance element 60. This solution however increases ineffective resistance and hence the resistance value of the resistance element 60 itself. Correspondingly, the current flowing through the resistance element 60 in the inoperative state is reduced and the produced voltage is lowered, thus resulting in reduced detection sensitivity of the analog signal. For those reasons, the above solution cannot be employed.
Furthermore, when the contact area between the electrically conductive rubber 50 and the resistance element 60 is increased, the pyramid-shaped fore end of the electrically conductive rubber 50 is contacted with the resistance element 60 such that the electrically conductive rubber 50 is pressed through the attachment surface 51b of the support member 51 so as to spread from the center of the resistance element 60 in opposite directions. However, when the actuating point P of the control lever 22 approaches a maximum limit of the movable range thereof, the amount of deformation of the electrically conductive rubber 50 is increased and a greater operating force is required to further compress the electrically conductive rubber 50.
Moreover, as shown in FIG. 8, when the control lever 22 is in the inoperative state, there is a gap left between the electrically conductive rubber 50 and the corresponding resistance element 60. This arrangement produces a dead zone in which the resistance value of the resistance element 60 (combined with the electrically conductive rubber 50) is not changed with initial movement of the actuating point P of the control lever 22.
As still another problem, when the resistance element 60 having a rectangular shape is used, there occurs a region in which the amount of movement of the actuating point P is not proportional to the resistance value of the resistance element 60 (i.e., linearity in relationship between them is deteriorated), during the process in which the electrically conductive rubber 50 is compressed with the movement of the actuating point P of the control lever 22. This problem is attributable to the fact that a compressive force applied to the pyramid-shaped electrically conductive rubber 50 and an elongation of the electrically conductive rubber 50 over the resistance element 60 are not always changed in linear relation. If it is attempted to modify the shape of the electrically conductive rubber 50 such that the amount of movement of the actuating point P is proportional to the resistance value of the resistance element 60, very difficult works would be necessitated to analyze deformations of the electrically conductive rubber 50 and obtain an optimum shape thereof.
It is an object of the present invention is to provide a signal input device which can certainly and fixedly hold the position of an electrically conductive rubber with respect to a resistance element, which can reduce a force required for operating a control, which can change the resistance value of the resistance element from an initial stage of movement of the control, which can change the resistance value of the resistance element substantially in proportion to the amount of movement of an actuating point of the control, and which can be applied to a controller for game machines.
To achieve the above object, according to the present invention, there is provided a signal input device for inputting a signal to an electronic device, wherein the signal input device comprises a control projecting out of a housing, a plurality of electrically conductive elastic members disposed in the housing and displaced depending on movement of the control, and a board disposed in the housing and having a plurality of resistance elements formed corresponding to the electrically conductive elastic members, the electrically conductive elastic members being able to change resistance values of the resistance elements by changing contact areas between the resistance elements and the electrically conductive elastic members, a part of each of the electrically conductive elastic members being rotatably supported on the board, whereby an analog signal corresponding to the resistance value of each of the resistance elements is inputted to the electronic device.
In the above signal input device, preferably, the electrically conductive elastic members are each held by a holding member having one end rotatably supported by a support provided on the board, and the electrically conductive elastic members are each pressed with rotation of the holding member to contact the resistance element over a gradually-increasing contact area from one edge to the other edge thereof, thereby changing the resistance value of the resistance elements.
In the above signal input device, preferably, the control is provided with a movement transmitting member movable upon movement of the control, a part of the movement transmitting member is held in abutment with the holding member, and the holding member is rotated with movement of the movement transmitting member to displace the electrically conductive elastic member.
In the above signal input device, preferably, the resistance elements are each constituted as a rectangular pattern, and the rectangular pattern is modified in shape for correction such that the resistance value of the resistance element is changed substantially linearly.
In the above signal input device, preferably, the device includes two sets of combination of the control and the plurality of electrically conductive elastic members displaced depending on movement of the control, the board includes the plurality of resistance elements provided for each of the two sets of combination of the control and the plurality of electrically conductive elastic members, and the analog signal is inputted to a game machine given as the electronic device, whereby the signal input device serves as a controller for the game machine.